The present invention relates to a valve guide insert for use in internal combustion engines and the like, and in particular to a thin-walled valve guide insert.
Valve guide inserts are commonly used in the construction and rebuilding of cylinder heads in internal combustion engines. More particularly, valve guide inserts are used to provide a wear resistant bearing surface between cylinder heads and the associated valves. Through extended use, valve guides within internal combustion engines can become worn, thereby allowing the associated valve to become sloppy within an associated cylinder. This sloppiness may result in improper seating of the valve or even the failure of the engine.
Cylinder heads associated with internal combustion engines are typically cast from iron or other non-durable metals. Valve guide inserts have become useful within the vehicle engine manufacturing industry by providing a hardened bearing surface between the valve guides and the associated valves, thereby increasing the useful life of the valve guides. Valve guide inserts have also become useful in the engine refurbishing industry by allowing for a worn guide to be broached and a valve guide insert to be inserted within the resized valve guide, thereby allowing for the continued use of the engine.
Heretofore, valve guide inserts were tubular shaped members formed of a hardened wear resistant metal. Typically, the valve guide inserts were press-fit into a valve guide bore of a cylinder head by way of a mechanical device that forcibly inserted the valve guide inserts within the valve guide bores. A broaching tool was then forced through the valve guide insert to form an interior bore for guiding the associated valve, as well as to create a tight fit of the valve guide insert within the valve guide floor.
A problem associated with use of thin-walled valve guide inserts is the tendency for the inserts to unacceptably deform or crumble during installation. This occurs due to the tight fit of the entire valve guide insert within the valve guide bore, as well as due to the force applied to the valve guide insert by the mechanical apparatus used to insert the valve guide insert into the valve guide bore. The thinner the insert, the more apt deformation will occur during the insertion process.
Another problem associated with using valve guide inserts in the refurbishing of cylinder heads is the requirement of re-boring the valve guide to allow placement of the valve guide insert therein. The more material that is required to be removed from the valve guide the greater the chance of cracking and destroying the valve guide during the re-boring procedure. Therefore, the thinner the wall thickness of the valve guide insert, the less material must be removed from the valve guide and the less chance of destroying the valve guide. However, the thinner the wall thickness of the valve guide insert, the greater the chance of unacceptable deformation or crumbling of the valve guide insert during the installation process.
Yet another problem associated with the use of thin-walled valve guide inserts is the tendency for the valve guide insert, if not properly installed to work lose from the associated valve guide, resulting in possible engine failure.
One aspect of the present invention is to provide a valve guide insert for lining and relining a valve guide bore in an internal combustion engine, wherein the internal combustion engine includes a valve with a valve stem, and the valve guide bore is configured to support the valve stem for reciprocal motion. The valve guide insert includes a thin-walled, cylindrically shaped, metallic tube made from a reformable bearing material suitable for slidably supporting a valve stem in a combustion engine, wherein the tube has a temporary retainer section and a long section, the retainer section defining a first outer diameter, and the long section defining a second outer diameter that is less than the first outer diameter, whereby the tube is configured to be dropped into a valve guide bore having a bore diameter less than the first outer diameter but greater than the second outer diameter.
Another aspect of the present invention is to provide a method for lining and relining a valve guide bore in an internal combustion chamber, wherein the internal combustion engine includes a valve with a valve stem, and the valve guide bore defines an outer diameter and is configured to support the valve stem for reciprocal motion. The method includes providing a thin-walled, generally cylindrically shaped, metallic tube having a long section and a retainer section, wherein the retainer section defines a first outer diameter, and the long section defines a second outer diameter that is less than the first outer diameter. The method further includes dropping the tube into a valve guide bore such that the retainer section having the first outer diameter of the tube contacts the inner diameter of the valve guide bore, and broaching the tube, thereby creating a tight fit of the tube within the valve guide bore of the internal combustion engine.
Yet another aspect of the present invention is to provide a valve guide insert for lining and relining a valve guide bore in an internal combustion engine, wherein the internal combustion engine includes a valve with a valve stem, and the valve guide bore is configured to support the valve stem for reciprocal motion. The valve guide insert includes a thin-walled, generally cylindrically shaped, tube made from reformable material and that has a first end and a length, wherein the first end has a retainer at the first end that defines a first outer diameter, and wherein the length has inwardly formed longitudinally-extending channels formed therein such that the length has a outer diameter smaller than the first outer diameter.
Yet still another aspect of the present invention is to provide a method that includes providing a cylinder head of an internal combustion engine, wherein the cylinder head includes a valve guide bore, and reboring the valve guide bore to a predetermined diameter. The method further includes providing a valve guide liner shaped to slip into the valve guide bore with finger pressure and inserting the valve guide bore liner into the valve guide bore.
Yet another aspect of the present invention is to provide a valve guide insert for lining and relining a valve guide bore in an internal combustion engine, wherein the internal combustion engine includes a valve with a valve stem, and the valve guide bore is configured to support the valve stem for reciprocal motion. The valve guide insert includes a thin-walled, cylindrically shaped, metallic tube made from reformable bearing material suitable for slidably supporting a valve guide stem in a combustion engine, wherein the tube has a wall thickness of 0.008 inches or less.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.